Women were also under-represented in the debate, outnumbered by men 3:1 on television and making up just 13% of all individuals in press coverage.

Non-Conservative representation in the top twenty was limited to Ukip's Nigel Farage, Corbyn and - just - Nicola Sturgeon, the SNP leader and First Minister of Scotland.

Curiously, interventions by Jean-Claude Juncker, President of the European Commission, and Angela Merkel, German Chancellor, mean they have featured more than Home Secretary Theresa May, McDonnell and Alan Johnson, who is leading of Labour’s In campaign.

Report co-author Professor John Downey said: “Over the last month of the campaign there has been sustained, almost ‘presidential’ focus on a handful of senior Tory party politicians.

"The dominance of the Conservative party and a select group of key figures has overshadowed the coverage of all other party representatives and other groups and institutions.

“Coverage about the referendum is still largely a ‘Tory story’ and a male dominated, ‘blue-on-blue’ tale at that.

“It has become self-evident that the Out campaign wishes to fight the referendum on the issue of immigration and the IN campaign on the economy, so it is very interesting to see which of these two topics is getting the most traction.”